1. Field of the Invention
The present invention provides new methods for preparation of various oxygen ring compounds (oxygen as an alicyclic ring member) including 2,5-disubstituted tetrahydrofurans, 2,6-disubstituted tetrahydropyrans, 2,7-disubstituted oxepanes and 2,8-oxocanes. The invention firer provides novel compounds and pharmaceutical compositions and therapeutic methods that comprise such compounds.
2. Background
Leukotrienes are recognized potent local mediators, playing a significant role in inflammatory and allegeric responses, including arthritis, asthma, psoriasis and thrombotic disease. Leukotrienes are produced by the oxidation of arachidonic acid by lipoxygenase. More particularly, arachidonic acid is oxidized by 5-lipooxygenase to the hydroperoxide 5-hydroperoxy-eicosatetraenoic acid (5-HPETE), that is converted to leukotriene A.sub.4, that in tun can be converted to leukotriene B.sub.4, C.sub.4, or D.sub.4. The slow-reacting substance of anaphylaxis is now known to be a mixture of leukotrienes C.sub.4, D.sub.4 and E.sub.4, all of which are potent bronchoconstrictors.
Efforts have been made to identify receptor antagonists or inhibitors of leukotriene biosynthesis, to prevent or minimize pathogenic inflammatory responses mediated by leukotrienes.
For example, European Patent Application Nos. 901171171.0 and 901170171.0 report indole, benzofuran, and benzothiophene lipoxygenase inhibiting compounds.
Various 2,5-disubstituted tetrahydrofurans have exhibited significant biological activity, including as lipoxygenase inhibitors. See U.S. Pat. Nos. 5,703,093; 5,681,966; 5,648,486; 5,434,151; and 5,358,938.
While such compounds are highly useful therapeutic agents, current methods for synthesis of least some of the compounds require lengthy routes, and reagents and protocols that are less preferred in larger scale operations, such as to produce kilogram quantities.
It thus would be desirable to have improved methods to substituted tetrahydrofurans and other cyclic oxygen compounds, particularly new syntheses that facilitate larger scale production of such compounds.